any recommendations for cheap/free PDF editor?

I've got NitroPDF on my laptop, but its a 32-bit only version and I'd like to have a 64-bit compatible version for my Win8 desktop.

I rarely use it, but occasionally need to edit PDFs in very basic ways, like add/remove a page here and there, merge two documents, and sometimes change a little text. So I think the most basic editor would provide the functionality I need, but I tried a couple of freeware programs and they didn't work very well. Maybe I gave up without learning them well enough, but they seemed very light in features, even for my minimalistic needs.